On microseisms recorded near a coast

Bossolasco, Mario; Cicconi, G.; Eva, C.

doi:10.1007/bf00876409

Cited by 6 publications

(4 citation statements)

References 4 publications

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“…Bossolasco et al . [] compared observations on top of an ocean‐front cliff and a site a few km inland composed of hard ground covered by a thin surface layer of alluvium, on the inland side of a harbor. At the coastal cliff, the spectral densities (i.e., energy level) of single and double frequency motions were approximately equal.…”

Section: Introductionmentioning

confidence: 99%

Ground motions on rocky, cliffed, and sandy shorelines generated by ocean waves

et al. 2013

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[1] We compare ground motions observed within about 100 m of the waterline on eight sites located on shorelines with different morphologies (rock slope, cliff, and sand beaches). At all sites, local ocean waves generated ground motions in the frequency band 0.01-40 Hz. Between about 0.01 and 0.1 Hz, foreshore loading and gravitational attraction from ocean swell and infragravity waves drive coherent, in-phase ground flexing motions mostly oriented cross-shore that decay inland. At higher frequencies between 0.5 and 40 Hz, breaking ocean waves and wave-rock impacts cause ground shaking. Overall, seismic spectral shapes were generally consistent across shoreline sites and usually within a few orders of magnitude despite the diverse range of settings. However, specific site response varied and was influenced by a combination of tide level, incident wave energy, site morphology, ground composition, and signal decay. Flexing and shaking increased with incident wave energy and was often tidally modulated, consistent with a local generation source. Flexing magnitudes were usually larger than shaking, and flexing displacements of several mm were observed during relatively large incident wave conditions (Hs 4-5 m). Comparison with traffic noise and earthquakes illustrate the relative significance of local ocean-generated signals in coastal seismic data. Seismic observations are not a simple proxy for wave-cliff interaction.

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Section: Introductionmentioning

confidence: 99%

Ground motions on rocky, cliffed, and sandy shorelines generated by ocean waves

et al. 2013

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“…Detailed observations of cliff top ground motions and local ocean waves are relatively scarce. Bossolasco et al [1973] compared observations of microseisms at a coastal cliff with observations a few km inland, on the inland side of a harbor. At the coastal cliff, the spectral densities (i.e., energy level) of single and double frequency motions were approximately equal.…”

Section: Introductionmentioning

confidence: 99%

Cross‐shore decay of cliff top ground motions driven by local ocean swell and infragravity waves

et al. 2012

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[1] Ground motions at the frequencies (between 0.01 and 0.1 Hz) of ocean infragravity and swell waves were observed on a cross-shore transect extending landward from the edge of a southern California coastal cliff. Cliff top ground motions are coherent and in phase with water level fluctuations at the cliff base. Vertical ground motions at infragravity and single frequencies decay rapidly with inland distance from the cliff edge (e-folding scale is about 12 m), and at the edge decrease by several orders of magnitude between high tide when waves reach the cliff base, and low tide when the waterline is about 50 m from the cliff base. The observed cross-shore decay scales are qualitatively consistent with gravitational loading and attraction of water waves at tidally modulated distances from the cliff base. At approximately constant distance from the waterline, ground motions vary roughly linearly with nearshore swell wave energy. In contrast to these locally forced ground motions, double frequency band (0.1-0.2 Hz) cliff top vertical ground motions are remotely generated with spatially uniform magnitudes approximately equal to those observed 14 km inland. Near the cliff edge, ground tilt dominates the observed large (relative to vertical) cross-shore acceleration at infragravity frequencies, contributes significantly to cross-shore acceleration at swell frequencies, and is a small fraction of cross-shore acceleration at higher frequencies.Citation: Young, A. P., R. T. Guza, P. N. Adams, W. C. O'Reilly, and R. E. Flick (2012), Cross-shore decay of cliff top ground motions driven by local ocean swell and infragravity waves,

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“…and D.F. microseisms are observed with variable relative intensity according to the distance of the coast (Bossolasco et al, 1973). Korhonen has moreover spectrally analysed sea waves registered on the Norwegian coast and found them peaked on primary frequency of microseisms in accordance with Miche (1944) and Longuet-Higgins (1953) mathematical computations.…”

Section: Recent Developmentsmentioning

confidence: 93%

Short review and recent results on microseisms

Bernard

1983

Geophysical Surveys

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Abstract. This paper endeavours, mostly in a bibliographical manner, to show the place of meteorological microseims among the whole of geophysics. Relations with swell are mentioned with their theoretical and practical consequences for the properties of both phenomena, and the work of members of the International Commissions on Microseisms is summarized, covering velocity and bearing of the waves, spectral analysis, relation with atmospheric circulation, and world-wide extension of these researches since the I.G.Y. In a recent project, undecennial variation of yearly means of microseismic disturbance, the maximum of which often occurs 2-3 years after sunspot maxima, is investigated using data from several stations. A similar variation is therefore inferred for atmospheric cyclones, and the brightness of other planets seems to vary in the same way. Changes in the solar constant are suggested as the physical influence responsible, and new recording devices are proposed to follow on an absolute scale the future behaviour of such an index of atmospheric disturbances.

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On microseisms recorded near a coast

Cited by 6 publications

References 4 publications

Ground motions on rocky, cliffed, and sandy shorelines generated by ocean waves

Ground motions on rocky, cliffed, and sandy shorelines generated by ocean waves

Cross‐shore decay of cliff top ground motions driven by local ocean swell and infragravity waves

Short review and recent results on microseisms

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